This invention relates to manually operated resuscitators of the kind used to assist or re-establish the breathing of a patient when that function has become impaired or has failed as a result of immersion, electric shock, or other accidental circumstance or illness detrimental to the normal breathing capability.
Such resuscitators conventionally comprise a recoilable self-inflating bag type reservoir into which breathable gas is drawn and from which the said gas may be directed to a patient, a valve assembly for directing a flow of breathable gas to the patient and exhaled gas from the patient to atmosphere, to which assembly is attached a face mask or endotracheal tube which in use is applied to the patient in known manner.
Improvements to manually operated resuscitators include supplemental oxygen supply to enrich the atmospheric air drawn into the reservoir during recoil which provides a low concentration of oxygen mixture, e.g. 50% oxygen in air.
Nevertheless an undesirable feature of such manually operated resuscitators is the rebreathable gas space which exists following patient exhalation when such exhalation gas is permitted to re-enter the reservoir during the period of recoil and inflation thereof. This reduces the amount of oxygen available to the patient during subsequent inhalation steps and permits exhaled carbon dioxide to be delivered back to the patient, which is considered to be detrimental to the patient.
A further undesirable feature exists in the multiplicity of component parts which generally are used in the assembly of the gas valve or valves. In such cases risk exists that a particular component may be misassembled or may even be omitted from the assembly. Such a complicated or multiple assembly as has been used requires a comparatively large occupant space which can at times become unwieldly in use and also tends to provide a too large capacity space for inhaled gas retention.